/Engine/Source/Runtime/Engine/Classes/Components/StaticMeshComponent.h
Shadow map memory usage is per light whereof lightmap data is independent of number of lights, assuming at least one.
bool true if the mesh has static lighting; false if not
virtual bool GetEstimatedLightAndShadowMapMemoryUsage ( int32 & TextureLightMapMemoryUsage, int32 & TextureShadowMapMemoryUsage, int32 & VertexLightMapMemoryUsage, int32 & VertexShadowMapMemoryUsage, int32 & StaticLightingResolution, bool & bIsUsingTextureMapping, bool & bHasLightmapTexCoords ) const